This invention relates to an optoelectronic module and to a method for stabilizing its temperature as set forth in the preambles of the respective independent claims.
From the prior art, for example from EP 0259888, it is known to design optoelectronic modules in such a way that the individual optoelectronic components, such as laser diodes or photodiodes, can be temperature-stabilized. To accomplish this, the active elements, which are formed or mounted on a substrate, are mounted by means of this substrate on a Peltier element, for example. To stabilize the output power and current consumption of, e.g., a laser diode, the substrate with the laser diode is cooled. A thermistor, which also rests on the substrate, is used as a sensor for the Peltier element. The thermistor requires a reference temperature to keep the temperature of the substrate, and thus of the laser diode, for example, stable. So far it has been usual to connect the thermistor directly to the housing by an electric connection. The temperature measurement of the thermistor thus takes place at the housing wall. Such a measurement may result in wrong temperature information being processed, since the housing has a temperature different from that of the substrate.
The optoelectronic module according to the invention, with the characterizing features of the first independent claim, has the advantage that the temperature measurement takes place directly on the substrate. The thermistor is connected to the substrate by an electric connection, and the temperature measurement takes place on the substrate, and thus close to the laser diode or photodiode. The extra cost of an additional electric wire connection is offset by the advantages of the assembly. The advantage is a temperature setting at the location of the laser diode itself, based on a temperature measurement which is also made at the location of the laser diode. This makes it possible to achieve very high temperature stability and thus ensure laser stability, which is of great importance for the transmission of high data rates.
By the method according to the invention, with the characterizing features of the second independent claim, temperature control is possible with a high degree of accuracy.
One embodiment of the invention will now be explained in detail with reference to the accompanying drawing showing schematically the construction of an optoelectronic module according to the invention.